The present invention relates to the sterile and total containment welding techniques for fluid filled plastic tubes. There are many applications which require a plastic tube to be connected to another plastic tube. Such applications include, for example, the taking of samples from a bioreactor, the treating of blood, CAPD and other medical applications. Prior patents generally dealing with this subject include U.S. Pat. Nos. 4,793,880; 4,610,670; 4,369,779; and 4,753,697.